Create autogenerate serial number column in GridView

In many Asp.net forums i found the question "How to generate a column as serial number at runtime of a gridview?". Also they have another concern was paging. Thats why here i want to share a simple code snippet with all. Which will help you to add a autogenerate number or sequential number or serial number in your GridView with less effort. Mind it the serial number will not come from Database.